Disposal of waste in urban areas has increasingly become a problem. Because of modern packages, mixture of trash and garbage from various foods and accumulation of such non-compactible trash as rubber tires special problems are introduced in disposal. Squeezing compactors in collection trucks are not adopted to handle tires and other substantially non-compressible materials, and although they improve packing efficiency of raw trash, they still inefficiently transport bulk trash over long distances to incinerator sites or dumps.
Conservation of energy is a concurrent problem in urban areas. Little of the combustible waste is used for useful fuel. The raw form in which combustibles are found is not generally adaptable to ready use as a fuel source. Papers, cardboard and plastic materials need be conformed in shape and density for efficient fuel use and mixtures therewith of damp waste such as garbage generally reduces the possibility of getting heat energy from the run-of-the-mill waste. Many incinerating plants require input of fuel for handling such waste. Also, the damp waste and garbage mixed with trash tends both to accumulate in conveyors and to spoil thereby causing problems both of sanitation and fouling of equipment.